/**
 * ClassName : PACKAGE_NAME.JieC
 * Desc : TODO
 *
 * @author : LINPQ
 * @date : 2020/12/9 18:32
 */
public class JieC {

    public static void main(String[] args) {
        System.out.println(f(3));
    }

//    f(x) = x*f(x-1); f(1) = 1;

    public static int f(int n){
        if(n==1){
            return 1;
        }else {
            return n*f(n-1);
        }
    }
}
